1. Field of the Invention
The present invention relates to a thinner composition.
2. Description of the Related Art
A photolithography process in a method for manufacturing a semiconductor device is one of important works, which includes applying a photosensitive resin composition to a wafer, transferring a pre-designed pattern thereto, and then suitably etching according to transferred pattern to thus form an electronic circuit.
Such a photolithography process may be sequentially conducted by: (1) a coating process of uniformly applying a photosensitive resin composition to a surface of the wafer; (2) a soft baking process of evaporating a solvent from the applied photosensitive film to adhere the photosensitive film to the surface of the wafer; (3) an exposure process of exposing the photosensitive film while repeatedly and sequentially conducting reduction projection of the circuit pattern on a mask using a light source such as ultraviolet rays, to thus transfer the pattern of the mask to the photosensitive film; (4) a development process of selectively removing some portions having different physical properties such as a difference in solubility occurred due to sensitization by exposure to the light source, using a developer; (5) a hard baking process of closely fixing the photosensitive film, which remains on the wafer after the development, to the wafer; (6) an etching process of etching a predetermined portion according to patterns of the developed photosensitive film; and (7) a stripping process of removing undesirable photosensitive film after the above processes, in this order.
Among the above photolithography processes, the spin coating process of providing the photosensitive film on a wafer and rotating the substrate to evenly spread the photosensitive film on the surface by a centrifugal force, may cause the photosensitive film to be gathered at an edge portion and a rear portion of the substrate due to the centrifugal force, to thus form a small spherical material. The spherical material may be peeled off during delivery of the substrate after the baking process, hence becoming a cause of particles in the apparatus, and also becoming a cause of defocus during exposure. Such undesirable photosensitive material may bring about contamination of an apparatus, hence reducing yield in the process for manufacturing the semiconductor device. Therefore, the undesirable photosensitive material is usually removed by installing injection nozzles at up and down of the edge portion and the rear portion of the substrate and injecting a thinner composition including an organic solvent component to the edge portion and the rear portion through the injection nozzles.
Factors of determining the performance of the thinner composition may include a rate of dissolution (‘dissolution rate’) and volatility thereof. The dissolution rate of the thinner composition determines how quickly and effectively dissolves and removes the photosensitive resin by the thinner composition, therefore, is very important factor. Specifically, when rinsing the edge portion of the substrate, a suitable dissolution rate is required to provide a smoothly treated cross-section. If the dissolution rate is too high, a photosensitive film attack may occur in rinsing the photosensitive film coated on the substrate. On the other hand, if the dissolution rate is too low, a so-called ‘tailing phenomenon,’ which is a phenomenon of flowing a partially dissolved photosensitive film tail, may occur in rinsing the photosensitive film coated on the substrate. In particular, since a diameter of the substrate is recently increased due to high integration and high densification of semiconductor integrated circuits, low revolution of a rotational speed (rpm) is unavoidable in a case of a rinsing process using a spin coater. In such a rinsing process, if a fluctuation occurs in the substrate due to the low revolution and the dissolution rate is not suitable within a contact rate of the thinner composition under injection, a bounding phenomenon may occur, and use of the thinner composition may be unnecessarily increased. As such, in the case of the low revolution rinsing process due to an increase in diameter of the substrate, it is necessary for the thinner to have a higher dissolution rate than any conventional high revolution rinsing process.
In addition, after removing the photosensitive resin, it is necessary for the thinner composition to be easily volatilized, and do not remain on the surface of a substrate. If the thinner composition cannot be volatilized but remain due to a very low volatility, the thinner residue itself may act as a contaminant in different processes, especially, a subsequent etching process, to cause a problem of decreasing the yield of semiconductor devices. On the other hand, if the volatility is too high, the substrate is quickly cooled to more increase a deviation in thickness of the coated photosensitive film, and the thinner may be easily volatilized into the atmosphere during use, thus causing a reduction in cleanliness.
Currently, i-line photoresist, KrF, ArF, EUV, KrF anti-reflection film, ArF anti-reflection film, and the like used as a photoresist in the semiconductor lithography process include different major components, respectively. Accordingly, controlling a content of an organic solvent for improving the solubility and applicabilities of these all components is required.
Korean Patent Laid-Open Publication No. 2011-21189 discloses a thinner composition including a hydrogen-bondable organic solvent, glycols, esters, and the like. In this regard, the composition has advantages of reducing an applying amount of photoresist, enabling uniform coating of the photoresist, and effectively removing undesirable photoresist applied to a peripheral portion or a rear portion of the substrate. However, due to the hydrogen bond, a viscosity of the thinner is increased but volatility is deteriorated to prevent volatilization of the thinner and remain the same on the substrate, hence leading to the tailing phenomenon at a photoresist removal interface. Furthermore, the thinner residue may act as obstructive particles in the subsequent process to cause a problem of reducing productivity of the production process.
Accordingly, there is a need for a thinner composition to have excellent solubility to various photoresist films, bottom anti-reflection coatings (BARCs), and underlayers, as well as favorable volatility, so as to exhibit excellent coating ability in applying photoresist, and thereby reducing an amount of the used photoresist.